How to Manage Pests

Pesticides: Water-Related Toxicology of Active Ingredients

Step 3. Risk values and pesticide properties

At this step WaterTox shows the potential pesticide hazards on high-risk soils. Note the following:

• hazard ratings are for soils at high risk for runoff and leaching.
• ratings assume that there will be no irrigation or rainfall within 7 to 10 days of pesticide application.
• your selections about application of the pesticide are shown. They have been used to determine the risks shown in the chart. To see how they affect the risk ratings, change the selections using the buttons at the bottom of the Web page.

All ratings, values, and adjusted ratings from the application information are derived from the USDA-NRCS Windows Pesticide Screening Tool, WIN-PST, unless otherwise noted.

• More information on WIN-PST

Ratings and values in the chart

Leaching potential indicates the tendency of a pesticide to move in solution with water and to leach below the root zone. The rating in the chart is the potential pesticide hazard to fish or to humans due to leaching from soils that are highly susceptible to leaching. If the soil is actually of a less-risky type, the potential hazard may be less. The hazard is based on long-term toxicity of the pesticide to fish and humans, not acute toxicity.

Ratings are VERY LOW, LOW, INTERMEDIATE, and HIGH. A VERY LOW or LOW rating indicates minimal movement and no need for mitigation. INTERMEDIATE and HIGH ratings indicate a greater potential for a pesticide to leach below the root zone, and measures to mitigate the impact may be needed. How is potential pesticide hazard to fish and humans, from leaching, determined?

Solution runoff potential indicates the tendency of a pesticide to move in surface runoff in the solution phase. The rating in the chart is the potential pesticide hazard to fish or to humans due to solution runoff from soils that are highly susceptible to runoff. If the soil is actually of a less-risky type, the potential hazard may be less. The hazard is based on long-term toxicity of the pesticide to fish and humans, not acute toxicity.

Ratings are LOW, INTERMEDIATE, and HIGH. A HIGH rating indicates the greatest potential for pesticide loss in solution runoff, and use of pesticides with INTERMEDIATE and HIGH ratings may need mitigating measures. How is potential pesticide hazard to fish and humans, from solution runoff, determined?

Adsorbed runoff potential is the tendency of a pesticide to move in surface runoff attached to soil particles. The rating in the chart is the potential pesticide hazard to fish or to humans due to adsorbed runoff from soils that are highly susceptible to runoff. If the soil is actually of a less-risky type, the potential hazard may be less. The hazard is based on long-term toxicity of the pesticide to fish and humans, not acute toxicity.

Ratings are LOW, INTERMEDIATE, and HIGH. A LOW rating indicates minimal potential for pesticide movement adsorbed to sediment, and no mitigation is required. INTERMEDIATE and HIGH ratings indicate a greater potential for a pesticide to move when attached to sediment, and measures to mitigate the impact may be needed. How is potential pesticide hazard to fish and humans, from adsorbed runoff, determined?

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